I have rhetoric Samsung Galaxy 18.4" Tablet and can't find how to view my photos on sdcard. Can you help me?

The only way to view the images from a SD card would be to go into the app you are using to view them (gallery or other app) and change that apps settings to located images on the card, or images on both the internal storage and the card.

However these must be compatible image files. If you have placed images on the SD card that are not readable by the app on the device, then they would have to be converted (off the device on a computer) into images that the tablet can read. Or you would have to get an app that can read said images.